Generally there exists a variety of different stacked assemblies and structures in the context of e.g. electronics and electronic products such as various electronic devices.
The motivation behind stacking electronics and other elements in a common structure may be as diverse as the related use contexts. Relatively often size savings, weight savings, cost savings, usability benefits, or just efficient integration of components in terms of e.g. the manufacturing process or logistics is sought for when the resulting optimized solution ultimately exhibits a multilayer nature. In turn, the associated use scenarios may relate to product packages or food casings, visual design of device housings, wearable electronics, personal electronic devices, displays, detectors or sensors, vehicle interiors, antennae, labels, vehicle and particularly automotive electronics, etc.
Electronics such as electronic components, ICs (integrated circuit) and conductors may be generally provided onto a substrate element by a plurality of different techniques. For example, ready-made electronics such as various surface mount devices (SKID) may be mounted on a substrate surface that ultimately forms an inner or outer interface layer of a multilayer structure. Additionally, technologies falling under the term “printed electronics” may be applied to actually produce electronics directly and additively to the associated substrate. The term “printed” refers in this context to various printing techniques capable of producing electronics/electrical elements from the printed matter, including but not limited to screen printing, flexography, and inkjet printing, through a substantially additive printing process. The used substrates may be flexible and printed materials organic, which is however, not necessarily always the case.
A substrate such as a plastic substrate film, may be subjected to processing, e.g. (thermo)forming or molding. Indeed, using e.g. injection molding or casting a plastic layer may be provided on the film, potentially then embedding a number of elements such as electronic components present on the film. The plastic layer may have different mechanical, optical, electrical, thermal, etc. properties. The obtained multilayer, or stacked, structure may be configured for a variety of purposes depending on the included features, such as electronics, and the intended use scenario and related use environment. It may, for instance, comprise connecting features for coupling with compatible features of a host device or generally host structure, or vice versa.
Yet, the concept of injection molded structural electronics (IMSE) actually involves building functional devices and parts therefor in the form of a multilayer structure, which encapsulates electronic functionality, typically as seamlessly as possible. Characteristic to IMSE is also that the electronics is often, not always, manufactured into a true 3D (nonplanar) form in accordance with the 3D models of the overall target product, part or generally design. To achieve desired 3D layout of electronics on a 3D substrate and in the associated end product, the electronics may be still provided on an initially planar substrate, such as a film, using two dimensional (2D) methods of electronics assembly, whereupon the substrate, already accommodating the electronics, may be formed into a desired three-dimensional, i.e. 3D, shape and subjected to overmolding, for example, by suitable plastic material that covers and embeds the underlying elements such as electronics, thus protecting and potentially hiding the elements from the environment. In addition to or instead, 3D assembly of electronics may be utilized.
Occasionally different elements, surfaces or devices, such as the ones consisting of or comprising an IMSE structure, should be provided with illumination capability that may bear e.g. decorative/aesthetic or functional, such as guiding or indicative, motive. For example, the environment of the element or device should be floodlit for increasing visibility in the gloom or dark during night-time, which may, in turn, enable trouble-free performing of various human activities typically requiring relatively high lighting comfort, such as walking or reading, to take place. Alternatively, the illumination could be applied to warn or inform different parties regarding e.g. the status of the host element or connected remote device via different warning or indicator lights. Yet, the illumination might yield the host element a desired appearance and visually emphasize its certain features by providing e.g. brighter areas thereon with desired color. Accordingly, the illumination could also be applied to instruct a user of the device about e.g. the location of different functional features such as keys, switches, touch-sensitive areas, etc. on the device surface, or about the actual function underlying the illuminated feature.
Thus, there are various use cases for illumination in conjunction with different IMSE structures and devices. As the illumination may not, however, always be a critical or sole feature of highest priority or of most importance in the associated product, and it may be at least occasionally considered a supplementary, optional feature only, the design and implementation of lighting features providing the desired illumination effect shall be duly executed. Weight and size requirements, elevated power consumption, additional design considerations, new process steps, and generally increased overall complexity of the manufacturing phase and of the resulting product are all examples of numerous drawbacks easily materialized as a side effect of adopting sub-optimum lighting features in the target solution. Yet, the appearance of the lighting effect and e.g. perceivability of lighting elements is one other issue. In some applications, the light sources should remain hidden or weakly exposed or the lighting effect should avoid easily recognizable hotspots.
Optically, many solutions that in principle accomplish their purpose in terms of light conveying or illumination performance in the context of IMSE still suffer from problems including light leakage, crosstalk and transmission loss (attenuation), which may be due to incoherent scattering and absorption among other reasons.